Urinary tract infection (UTI) is markedly overrepresented in women and is the kidney or urologic disease prompting the most visits of patients to physicians and most frequently found on hospital discharge diagnoses. The objectives of this Program are to discover the molecular and cellular interactions of bacteria with urinary tract epithelia which contribute to UTI and to begin to apply this knowledge to prevent or treat it. Our overall strategy is to use the powerful tools of molecular and cellular biology to study interaction of uropathogenic bacterial strains with the type of human urinary epithelial cells which they infect and to confirm this pathogenesis in an established experimental animal model. By such means, we intend not only to determine mechanisms of infection by known bacterial virulence factors but also to generate hypotheses about heretofore unknown mechanisms of infection. We believe that a special feature of this Program is its integration of bacterial genetics and host biology. We have bacterial isolates from pyelonephritis, cystitis, and asymptomatic bacteriuric cases and from feces of controls. Investigators in our group now routinely manipulate bacterial genes. Our central tenet is that target cells for lumenal urinary organisms are bladder and renal epithelial cells. The usual scheme will be to observe an interaction of bacterial with cultured human urinary epithelial cells, develop assays to measure this interactions, and then determine probable mechanisms of pathogenesis by manipulating the bacterial genome or the epithelial cell response. To accomplish these objectives, we have an experienced team of molecular biologists, cellular biologists, animal model specialists, and pathologists. The intentions of this Program will be: 1) to understand virulence factors of Proteus mirabilis with an intent to develop a vaccine; 2) to evaluate renal epithelial cells as amateur phagocytes, studying mechanisms of bacterial internalization, fates of the cell and of the internalized bacteria, and proteins differentially expressed by infected cells; and 3) to begin to apply our techniques to the study of E. coli cystitis, identifying adhesions for human bladder epithelial cells and investigating the role of internalization, hemolysin, and cytotoxic necrotizing fact or in the pathogenesis of cystitis.